New criteria for issuance of Frost Advisories and Freeze Warnings

The National Weather Service office in Paducah has adopted new criteria for the issuance of Frost Advisories and Freeze Warnings.

Spring criteria: There is no longer a fixed date for the initiation of these advisory and warning products. The seasonal initiation of these products will be in coordination with agricultural weather specialists. These specialists include county agricultural extension agents and university researchers.

Fall criteria: Issuances will cease for the season once a widespread killing freeze has occurred. Issuances may be restarted prior to November 1 if there has been a lengthy period of unusually warm weather following the first killing freeze. Any restart would be coordinated with agricultural weather specialists. If a killing freeze does not occur prior to November 1, issuances will continue past that date.

Definitions:

Frost: The deposition of ice crystals directly on the surface of exposed objects. In the right conditions (clear skies, light winds) frost can occur when observed air temperatures are several degrees above freezing.

Freeze: When observed air temperatures fall to 32 degrees or lower.

Killing freeze: When observed air temperatures fall to 30 degrees or lower for at least two consecutive hours.

Frost Advisory: Issued when frost is forecast to occur at most locations in a particular region.

Freeze Warning: Issued when a freeze is expected to occur at most locations in a particular region.